Disorder effects in GaAs/In x Ga 1–x As/GaAs quantum well delta doped with Mn

We present results of magnetic and transport measurements of GaAs/Ga1–xInxAs/GaAs quantum well structures containing a Mn δ-layer separated from the quantum well by a 3 nm spacer. The kink observed in temperature dependence of the sample resistance and anomalous Hall effect give a hint for carrier spin polarization. Magnetization measurements show an unusual shifted hysteresis loop. The observed results are treated in the frame of long range fluctuation potential model. Parameters of the potential are estimated. It is shown that disorder determines the structural properties in spite of the hole mobility of about 2000 cm2/(V·s) being much higher than in presently known ferromagnetic two-dimensional structures. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)